1. Field of the Invention
The present invention relates generally to a switch with contacts, and more particularly, to a switch applicable to a power window switch for vehicle use, for example.
1. Description of the Prior Art
As this type of switch, a slide switch, a seesaw switch, and a slide-type seesaw switch have been conventionally known. Representatives of the prior art switch will be described with reference to the drawings.
FIG. 17 is a cross-sectional view showing a switch main body of a slide switch, wherein a slider 111 operated from outside is movably supported on a terminal base 113 having fixed contacts, and a movable contact 116 is supported in the slider 111 and is pushed by a spring 117. When the slider 111 is slid, the movable contact 116 is moved. Consequently, a normally open fixed contact 115o and a common fixed contact 115m are switched.
FIG. 18 is a cross-sectional view showing a seesaw switch, wherein an operation knob 104 is rotatably supported on a switch case 103, and a pushing member 108 biased by a spring 107 is held in the operation knob 104. The pushing member 108 pushes a movable contact member 116 supported in seesaw fashion on a terminal base 113 which has fixed contacts 115. When the operation knob 104 is rotated, a point at which the pushing member 108 pushes the movable contact member 116 is displaced, and the movable contact member 116 is rotated in seesaw fashion. Consequently, the contacts are switched.
In these types of switches, however, the spring or the pushing member merely pushes the movable contact. Therefore, the speed at which the contacts are separated from each other is determined by the speed at which the slider (or the knob) is operated.
In a state where the fixed contact and the movable contact are brought into contact with each other, and a current flows therethrough, an arc is liable to generate when the movable contact is separated from the fixed contact. If the speed at which the movable contact is separated from the fixed contact is low, arc energy is increased.
A power window switch for vehicle use, for example, may, in some cases, be subjected to tampering for reducing the speed at which the slider or the knob is operated. Consequently, the speed at which contacts are separated from each other is reduced so that arc energy is extremely increased. Therefore, the slider composed of a resin molded part is deformed due to heat generated by switching the contacts, and the durability of the switch is decreased by the abrasion of the contacts. Further, a high-cost material having good heat resistance or a high-cost and large-sized contact material having good arc resistance must be used.